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United States Patent |
5,349,080
|
Harris
|
September 20, 1994
|
Ester-functional monomers and polymers prepared from same
Abstract
An unsaturated ester monomer having the structure:
##STR1##
wherein R.sup.1 is hydrogen or methyl; R.sup.2, R.sup.3 and R.sup.4 are
each independently lower alkyl of 1 to about 4 carbons; and Z is nothing
or is a divalent radical having 1 to about 20 carbons.
Inventors:
|
Harris; Rodney M. (Chicago, IL)
|
Assignee:
|
The Sherwin-Williams Company (Cleveland, OH)
|
Appl. No.:
|
176609 |
Filed:
|
January 3, 1994 |
Current U.S. Class: |
560/81 |
Intern'l Class: |
C07C 069/76 |
Field of Search: |
560/81
554/116
|
References Cited
U.S. Patent Documents
3594415 | Jul., 1971 | Zisman et al. | 260/515.
|
3803254 | Apr., 1974 | Hattori et al. | 260/669.
|
4275229 | Jun., 1981 | Mylonakis et al. | 562/459.
|
Foreign Patent Documents |
0723674 | Dec., 1965 | CA | 260/479.
|
Primary Examiner: Dees; Jose G.
Assistant Examiner: Conrad, III; Joseph M.
Attorney, Agent or Firm: McDonald; Robert E., Tan; Steven W., Boehlefeld; Heidi A.
Claims
The invention claim is:
1. An unsaturated ester monomer having the structure:
##STR6##
wherein R.sup.1 is hydrogen or methyl; R.sup.2, R.sup.3 and R.sup.4 are
each independently lower alkyl of 1 to about 4 carbons; and Z is nothing
or is a divalent radical having 1 to about 20 carbons.
2. The monomer of claim 1 wherein R.sup.1 is hydrogen.
3. The monomer of claim 1 wherein R.sup.1 is methyl.
4. The monomer of claim 1 wherein R.sup.2, R.sup.3 and R.sup.4 are each
ethyl.
5. The monomer of claim 1 wherein Z is nothing.
6. The monomer of claim 1 wherein Z is a divalent polymethylene chain
--(--CH.sub.2 --).sub.n -- wherein n is 1 to 20.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention involves novel polymerizable monomers having pendent ester
groups and polymers prepared from those monomers. The monomers have the
structure:
##STR2##
wherein R.sup.1 is hydrogen or methyl; R.sup.2 R.sup.3 and R.sup.4 are
each independently lower alkyl of 1 to about 4 carbons; and Z is nothing
or is a divalent alkyl radical having 1 to about 20 carbon atoms.
Preferred divalent alkyl radicals are methylene chains--(--CH.sub.2
--).sub.n --wherein n is 1 to 20.
This invention also relates to polymers obtained by polymerizing, under
free radical addition polymerization conditions, (i) the unsaturated ester
monomer of this invention; and (ii) optionally, at least one other
unsaturated monomer copolymerizable with the unsaturated ester monomer.
The monomers are also useful as reactive diluents and as precursors for
acid and/or anhydride-functional monomers.
2. Description of the Prior Art
Unsaturated, polymerizable esters, such as butyl acrylate, methyl
methacrylate, methyl crotonate, or ethyl tiglate and polymers or
copolymers incorporating these materials are known in the art. By the
selection of one or more of these esters, the characteristics of a polymer
may be tailored to provide a desired glass transition temperature,
hardness, flexibility or other desired property. The prior art has not,
however, taught polymers obtained by the polymerization of the novel
styrene-based ester monomers of this invention.
BRIEF SUMMARY OF THE INVENTION
This invention involves polymerizable unsaturated monomers having pendent
ester functionality, and to polymers derived by polymerizing the ester
monomer through its unsaturation either as a homopolymer or, preferably,
in combination with one or more additional copolymerizable monomers. The
esters of this invention can be utilized to alter the glass transition
temperature, solubility, hardness, flexibility, crystalinity or other
physical or performance property of a copolymer by incorporating these
novel monomers into the polymer backbone by free radical polymerization.
Furthermore, since the unsaturated esters of this invention are styrene
based materials, their reactivity ratios with other polymerizable monomers
such as styrene and (meth)acrylate monomers under free radical
polymerization conditions will be different than the reactivity ratios of
the common prior art (meth)acrylate esters with those same copolymerizable
monomers. Therefore, the monomers of this invention can provide a way to
incorporate ester side chains while altering the arrangement of other
monomers along the polymeric backbone compared to the use of the common
prior art unsaturated esters. Additionally, since the ester groups of the
monomer can be, if desired, fully or partially hydrolyzed, either before
or after polymerization to produce acid-functional monomers and/or
polymers, these ester monomers of this invention have special utility when
utilized as precursors for those acid-functional materials.
Accordingly, one object of this invention is to provide novel styrene based
ester monomers. Another object is to provide polymers and copolymers
incorporating the ester monomers. Another object is to provide new
unsaturated esters which are readily hydrolyzable to acid functionality.
These and other objects of the invention will become apparent from the
following discussions.
DETAILED DESCRIPTION OF THE INVENTION
The unsaturated styrene based ester monomers of this invention can be
conveniently prepared by the reaction of the anion of a
trialkyl-1,1,2-ethanetricarboxylate (such as
triethyl-1,1,2-ethanetricarboxylate), with a vinyl benzene alkyl halide
(such as vinyl benzyl chloride). The vinyl benzene alkyl halide has the
general structure:
##STR3##
wherein R.sup.1 and Z are as defined above and X is a halogen atom. The
vinyl benzene alkyl halides of various lengths of Z can be readily
prepared by a variety of methods known in the art. For example, Grignard
reaction synthesis of the vinyl benzene alkyl halides are representatively
set forth in M. L. Hallensleben, Angew. Makronol. Chem., 31 147 (1973),
and Montheard et al. J. Polym. Sci. Part A., Polym. Chem., 27 (8), 2539
(1989). For cost and availability of starting materials, it is especially
preferred that Z be nothing or be lower alkyl of 1 to about 4 carbons.
Vinyl benzyl chloride, where Z is nothing, R.sup.1 is hydrogen and X is
chlorine, is especially preferred.
The trialkyl-1,1,2-ethanetricarboxylate has the general structure:
##STR4##
wherein R.sup.2, R.sup.3 and R.sup.4 are lower alkyl of 1 to about 4
carbons. Due to cost and reactivity, triethyl-1,1,2-ethanetricarboxylate
is especially preferred.
The reaction to produce the preferred ester-functional monomer is
representatively shown below wherein the
trialkyl-1,1,2-ethanetricarboxylate is triethyl-1,1,2-ethanetricarboxylate
and the vinyl benzene alkyl halide is vinyl benzyl chloride:
##STR5##
The preparation of the anion of the trialkyl-1,1,2-ethanetricarboxylate is
conveniently accomplished by mixing ethanolic sodium ethoxide with the
tricarboxylate and refluxing the solution for five to ten minutes.
Typically the sodium ethoxide will be present at a level to provide about
0.8 to about 1.1 moles of sodium ethoxide for each mole of tricarboxylate.
The anion of the tricarboxylate can then be reacted with the vinyl benzene
alkyl halide by mixing the two materials in an approximately 1 to 1 mole
ratio and by maintaining the reaction at reflux, in the presence of small
amounts (e.g. 500 ppm of the total reaction mixture) of polymerization
inhibitors, for 1 to about 3 hours to prepare the vinyl benzene
alkyl-1,1,2-ethane tricarboxylate.
In one use of the monomer of the invention, the vinyl benzene
alkyl-1,1,2-ethane tricarboxylate could be hydrolyzed to produce the
corresponding tricarboxylic acid by reaction with base, such as sodium
hydroxide or potassium hydroxide, followed by acidification.
Alternatively, the hydrolysis can be accomplished by direct reaction of
the tricarboxylate with aqueous acid such as aqueous hydrochloric acid.
Base hydrolysis is generally preferred and can be readily conducted by
admixing an aqueous and/or ethanolic solution of sodium hydroxide or
potassium hydroxide and maintaining the reaction mixture at reflux until
the reaction is complete (typically 3 to 5 hours). The salt product can be
collected by filtration and the tricarboxylic acid is then generated by
acidifying an aqueous solution of the salt to a pH less than about 3,
typically by using dilute acid such as aqueous hydrochloric acid.
The polymerization of the novel monomers of this invention either alone or
with other unsaturated copolymerizable monomers, such as acrylic or
methacrylic monomers or styrene, proceeds at excellent yield and can
produce polymers having excellent performance characteristics.
The polymers which incorporate the monomers of this invention could
conveniently be prepared by polymerizing the styrene based ester monomer,
and, normally, at least one other copolymerizable monomer under free
radical addition polymerization conditions. Typically, the polymerization
would be conducted in an inert solvent and in the presence of an
initiator, such as a peroxide or azo compound, at temperatures ranging
from 35.degree. C. to about 200.degree. C., and especially 75.degree. C.
to about 150.degree. C. Representative initiators include di-t-butyl
peroxide, cumene hydroperoxide, and azobis(isobutyronitrile).
The mixture of monomers used to prepare the polymers would typically
comprise from 1 to 100, and especially 5 to about 85 percent by weight of
the styrene based ester monomer. The remainder of the mixture of monomers
would be comprised of at least one other unsaturated monomer
copolymerizable with the styrene based ester monomer. If it is desired to
generate a reactive polymer, suitable unsaturated monomers containing
potentially reactive sites such as hydroxy, epoxy, acid or amine groups
can be incorporated into the polymer along with the styrene based esters.
Typically, the styrene based ester monomers would be copolymerized with
one or more monomers having ethylenic unsaturation such as:
(i) acrylic, methacrylic, crotonic, tiglic, or other unsaturated acids or
derivatives thereof, such as: acrylic acid, methacrylic acid, methyl
acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl
acrylate, isobutyl acrylate, ethylhexyl acrylate, amyl acrylate,
3,5,5-trimethylhexyl acrylate, methyl methacrylate, ethyl methacrylate,
propyl methacrylate, dimethylaminoethyl methacrylate, isobornyl
methacrylate, ethyl tiglate, methyl crotonate, ethyl crotonate,
2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl
acrylate, 4-hydroxybutyl methacrylate, 2-hydroxypropyl methacrylate,
3-hydroxybutyl acrylate, 4-hydroxypentyl acrylate, 2-hydroxyethyl
ethacrylate, 3-hydroxybutyl methacrylate, 2-hydroxyethyl chloroacrylate,
diethylene glycol methacrylate, glycidyl acrylate, glycidyl methacrylate,
tetra ethylene glycol acrylate, etc.;
(ii) vinyl compounds such as vinyl acetate, vinyl propionate, vinyl
butyrate, vinyl isobutyrate, vinyl benzoate, vinyl m-chlorobenzoate, vinyl
p-methoxybenzoate, vinyl .alpha.-chloroacetate, vinyl toluene, vinyl
chloride, paravinyl benzyl alcohol, etc.;
(iii) styrene-based materials such as styrene, .alpha.-methyl styrene,
.alpha.-ethyl styrene, .alpha.-bromo styrene, 2,6-dichlorostyrene, etc.;
(iv) allyl compounds such as allyl chloride, allyl acetate, allyl benzoate,
allyl methacrylate, etc.;
(v) other copolymerizable unsaturated monomers such as ethylene,
acrylonitrile, methacrylonitrile, dimethyl maleate, isopropenyl acetate,
isopropenyl isobutyrate, acrylamide, methacrylamide, and dienes such as
1,3-butadiene, etc.
The free radical addition polymers of this invention could typically be
used as lacquers or as reactive polymers and would have application in
adhesives, coatings, inks, plastics, chemical additives and fibers. Where
the polymers are required to be of the reactive crosslinking type,
suitable functional monomers which can be used include acrylic or
methacrylic acid, hydroxy ethyl acrylate, 2-hydroxy propyl methacrylate,
glycidyl acrylate, tertiary-butyl amino ethyl methacrylate, etc. The
polymer may, in such a case, be used in combination with a crosslinking
agent which would be reactive with the functional groups of the polymer.
Typical crosslinking agents would include polyisocyanates, polyepoxides or
nitrogen resins such as the condensates of an aldehyde such as
formaldehyde with a nitrogenous compound such as urea, melamine or
benzoguanamine or a lower alkyl ether of such a condensate.
The following examples have been selected to illustrate specific
embodiments and practices of advantage to a more complete understanding of
the invention. Unless otherwise stated, "parts" means parts-by-weight and
"percent" is percent-by-weight. The starting raw materials utilized in
these examples are commercially available. The vinyl benzyl chloride is a
70/30 meta/para isomer commercially available from Dow Chemical Company.
The sodium metal, diethyl malonate, ethyl chloroacetate, acetic anhydride,
butylated hydroxy toluene, and, unless otherwise indicated, the
triethyl-1,1,2-ethanetricarboxylate, were obtained from Aldrich Chemical
Company. The absolute ethanol was obtained from USI-Quantum Chemical
Company.
EXAMPLE A
Triethyl-1,1,2-ethane tricarboxylate
A solution of sodium ethoxide in ethanol was prepared by slowly adding
559.4 g sodium metal into 7890 g of absolute ethanol. Next, 3891.9 g of
diethyl malonate was added to the ethanol solution over 45 minutes at an
initial temperature of 25.degree. C. The mixture was homogenized by
heating at 50.degree. C. for 40 minutes. Next, 3000 g ethyl chloroacetate
was slowly added over approximately 90 minutes, while the reaction mixture
was maintained at 40.degree.50.degree. C. with occasional warming. The
mixture was then heated at reflux for 2 hours, then cooled to room
temperature.
The mixture was worked-up by stripping off approximately two-thirds of the
ethanol (.about.750-800 ml). The residue was then washed with water and
extracted with toluene. The toluene solution was dried over magnesium
sulfate, followed by removal of the toluene to give a dark red residue.
The product residue was distilled under reduced pressure to give 3252 g
(approximately 54.3% yield) of triethyl-1,1,2-ethane tricarboxylate in
.about.97% purity.
EXAMPLE B
Triethyl 1-(3/4-vinyl benzyl)-1,1,2-ethane tricarboxylate
An ethanol solution of sodium ethoxide was prepared by adding 283 g of
sodium metal over 8 hours to 6404 g of ethanol (maximum temperature
60.degree. C.). Triethyl-1,1,2-ethane tricarboxylate (Example A, 3156.9 g)
was then added over 20 minutes to the ethanol solution (maximum
temperature 30.degree. C.). The mixture was then heated at reflux for 5-10
minutes, then cooled to 25.degree. C. Next, 1816.3 g of vinyl benzyl
chloride was added over 40 minutes, while keeping the temperature under
35.degree. C. A small amount of butylated hydroxy toluene inhibitor was
added. The mixture was heated at reflux for 2 hours and 20 minutes and
then allowed to cool to room temperature.
The reaction mixture was neutralized (pH.about.7) with glacial acetic acid,
and approximately two-thirds of the ethanol was stripped off under reduced
pressure. Sodium chloride was filtered off. The unpurified styryl
methylene triester/ethanol solution (63.6% NVM in ethanol) was then
utilized to produce the corresponding tricarboxylic acid as shown in
Example E.
EXAMPLE C
Triethyl 1-(3/4-vinyl benzyl)-1,1,2-ethane tricarboxylate
A sodium ethoxide/ethanol solution was prepared by slowly adding 16.02 g of
sodium metal to 365 g of absolute ethanol with slow stirring. The mixture
was then heated at reflux for 5-10 minutes. Triethyl-1,1,2-ethane
tricarboxylate (180 g from Aldrich Chemical Company) was added over 20
minutes to the mixture at room temperature. The mixture was heated at
reflux for 5-10 minutes, then cooled to 25.degree. C. Next, 112.9 g of
vinyl benzyl chloride was added over 20 minutes (maximum temperature of
the reaction mixture was 45.degree. C.). A small amount of butylated
hydroxy toluene inhibitor was added. The mixture was heated to reflux for
2 hours, then cooled to room temperature.
The reaction mixture was neutralized (pH.about.7) with glacial acetic acid.
About two-thirds of the ethanol was stripped off under reduced pressure.
Six hundred sixty-five milliliters of deionized water was added and the
product was extracted with toluene. The combined toluene extracts were
dried over sodium sulfate. Removing the volatiles with rotary evaporation
produced 255.2 g of triethyl-1-(3/4-vinyl benzyl)-1,1,2-ethane
tricarboxylate as a yellow liquid in an isolated yield of 96% of theory.
NMR and infrared spectral data confirmed the structure of the
tricarboxylic product.
One potential utility for the styrene based ester monomers of this
invention is their use as precursors for acid-functional monomers and
polymers. Acid-functional monomers and polymers are useful for their
reactivity with other groups such as hydroxyl or epoxy and also can be
neutralized with a base such as ammonia to provide water dispersibility.
Example D and E show the production of such acid-functional monomers.
EXAMPLE D
1-(3/4-Vinyl benzyl)-1,1,2-ethane tricarboxylic acid
An aqueous/ethanolic potassium hydroxide solution was prepared by slowly
mixing 2805 ml of absolute ethanol and 147.5 ml of deionized water. A
small amount of butylated hydroxy toluene inhibitor was added. Potassium
hydroxide (363 g) was added slowly keeping the temperature below reflux.
The mixture was then cooled to 30.degree. C. and 240 g, (approximately
0.662 mol) of the crude product of the vinyl benzyl triester of Example C
was quickly added. The mixture rapidly turned cloudy and then became
homogeneous upon heating to reflux. An additional small amount of
butylated hydroxy toluene inhibitor was again added and reflux was
continued for 4 hours. The precipitate laden mixture was then allowed to
cool to room temperature. The tricarboxylate salt was collected by suction
filtration, then dissolved in deionized water (800 ml) and neutralized
with dilute aqueous hydrochloric acid (5:1 conc. HCl/H.sub.2 O vol. ratio)
to a pH <2. Two additions of approximately 3000 ml each of anhydrous
acetone was added to the acidified solution and the potassium chloride
precipitate was filtered off. The acetone was then stripped off and the
process was then repeated. The remaining volatiles were then removed under
reduced pressure to give an isolated yield of 113.1 g (74.4%) of an off
white solid (mp 112.5.degree.-125.degree. C. decomposed). NMR, infrared
and acid dissociation constants data were used to characterize the
tricarboxylic acid product. In water, aqueous potassium hydroxide
titration identified the Pka's of the three carboxylic acid groups as
2.60; 4.59 and 8.06.
EXAMPLE E
1-(3/4-Vinyl benzyl)-1,1,2-ethane tricarboxylic acid
An aqueous potassium hydroxide solution (612 g, 109.2 mol of potassium
hydroxide in 2490 g of water) was slowly added to 6375 g (11.17 mol) of
the unpurified vinyl benzyl triester/ethanol solution of Example B,
(36.47% NVM) containing a small amount of butylated hydroxy toluene
inhibitor, while keeping the exothermic reaction below reflux. An
additional small amount of butylated hydroxy toluene was again added. The
mixture was then heated to reflux for 4 hours, and cooled to room
temperature. The precipitated solid tricarboxylic salt was collected by
filtration. Additional ethanol (12000 g) and then propanol (12000 g) were
used to precipitate out the remaining salt which was collected by
filtration.
A dispersion of the tricarboxylate salt was made in anhydrous acetone. The
salt was neutralized by acidifying the mixture with a concentrated
hydrochloric acid (HCl)/water solution (5:1 volume ratio) to a pH of <2.
The acetone, aqueous HCl solution was then treated with a 2:1
hexane/toluene mixture. Stripping volatiles from the residual solution
yielded 2777 g of an orange solid crude product. NMR and infrared spectral
data confirmed the structure as the desired tricarboxylate. The product
also contained some neutralized potassium carboxylate salt.
Another potential utility of the ester monomers of this invention is their
use as polymerizable components of free radical addition polymers. A
theoretical production of such a polymer is given in Example F.
EXAMPLE F
Hydroxy-Functional Copolymer
A representative hydroxy-functional polymer incorporating the styrene based
ester of this invention could be prepared, in a representative fashion, as
follows:
A reaction vessel equipped with a mechanical stirrer, water cooled
condenser, nitrogen inlet, water trap, thermometer and heating mantel
could be charged with 172.5 parts of n-butyl acetate and heated to
approximately 230.degree. F. and a monomer premix comprising 91.2 parts of
methyl methacrylate, 58 parts of butyl acrylate, 58 parts of hydroxy ethyl
methacrylate, 15 parts of the monomer of Example C, 54 parts styrene and
an initiator premixture composed of 11.5 parts of n-butyl acetate and 5.7
parts of 2,2'-azobis(2-methylbutyronitrile) could be metered
simultaneously into the polymerization reactor at a constant rate for
approximately 4 hours. The reaction temperature could be maintained for an
additional 2 hours after the addition was completed and then allowed to
cool to yield the hydroxy-functional acrylic polymer incorporating the
styrene based ester of this invention. Such a hydroxy-functional polymer
could be utilized in combination with a typical crosslinking agent, such
as polyisocyanate or a melamine curing agent to provide curable coating
compositions.
While this invention has been described by a specific number of
embodiments, other variations and modifications may be made without
departing from the spirit and scope of the invention as set forth in the
appended claims.
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